Blue hydrogen: is it green or grey?
Blue Hydrogen could help to tackle climate change, but hidden emissions mean that without proper controls, it might do more harm than good.
Owing to the decreasing costs in production, hydrogen is now moving towards the centre of green innovations that could help abate the climate crisis. Today, 17 governments have released hydrogen strategies, more than 20 governments have publicly announced they are working to develop strategies, and numerous companies are seeking to tap into hydrogen business opportunities (IEA Global Hydrogen Review 2021). Under the 2050 net zero emissions roadmap published by the International Energy Agency (IEA), hydrogen is expected to account for 6% of the carbon dioxide (CO2) emission reductions. Conflicts arise however in how we produce this hydrogen — will it truly be a greener alternative, or will it simply enable business as usual for fossil fuel companies?
How much hydrogen do we need for net zero?
So, hydrogen is a modest but significant chunk of the energy production required to reduce greenhouse gases (GHG) emissions. In real terms, this means that we need to produce 530 million tonnes (Mt) annually by 2050, up from about 90 Mt today under the IEA’s net zero roadmap.
But the question is, what form, or to use the emerging definitions, what colour will this hydrogen take?
Producing hydrogen by way of fossil fuel use is dubbed brown or grey hydrogen: coal or natural gas is burned in the production and CO2 is emitted into the atmosphere. At the other end of the spectrum is green hydrogen, whereby renewable energy sources (RES) are used to power an electrolyser to split water into its constituent parts of hydrogen and oxygen. Somewhere between these is blue hydrogen, and it is in this murky middle ground that suspicions have formed.
Essentially, blue hydrogen is using carbon capture (CC) to abate the CO2 emission released from grey hydrogen, from which the captured carbon will be stored or further utilised in another process, such as in the chemicals or cement industry.
Under the IEA’s net zero strategy, by 2050 we will have a mix of hydrogen with around 60% coming from electrolysers (green hydrogen) and involving CC from natural gas usage (blue hydrogen). It is not considered that coal production with CC will be in use at this point. Why is green hydrogen not higher? In the projections, even at only 60% of the required hydrogen coming from 3,600 gigawatts (GW) of renewable electricity is needed. To put this into perspective, IRENA estimate the global electricity production from solar and wind will be 13,000 GW. The extra 2,400 GW needed to make 100% green hydrogen would therefore require an 18% increase in an already best-case scenario for renewable energy production.
The transition period is also an important consideration. About half of the hydrogen used will be in heavy industry (mainly steel and chemicals), where rapid decarbonisation is needed. So, where the best-case alternatives of green hydrogen are not available, is it a good idea to focus on blue hydrogen production to decarbonise these industries, or is this another case of greenwashing, allowing fossil fuel use to continue with the illusion of mitigating climate change?
The problem with blue hydrogen
Concerns over the use of blue hydrogen we summed in the Just Have a Think (JHaT) episode: Blue Hydrogen. The greatest fossil fuel scam in history?, which also provides a succinct overview of the different forms of hydrogen production. The episode largely draws on a single paper by Howarth & Jacobsen (H&J) entitled How green is blue hydrogen, published in July 2021. Both sources paint a damning picture of blue hydrogen, with Dave Borlace of JHaT suggesting in that and other episodes that the shift to blue hydrogen is being promoted by the fossil fuel industry as a way to continue business as usual. This has, of course, caused some backlash from the industry.
H&J claim that:
“For our default assumptions (3.5% emission rate of methane from natural gas and a 20- year global warming potential), total carbon dioxide equivalent emissions for blue hydrogen are only 9%- 12% less than for gray hydrogen. While carbon dioxide emissions are lower, fugitive methane emissions for blue hydrogen are higher than for gray hydrogen because of an increased use of natural gas to power the carbon capture. Perhaps surprisingly, the greenhouse gas footprint of blue hydrogen is more than 20% greater than burning natural gas or coal for heat and some 60% greater than burning diesel oil for heat, again with our default assumptions.”
This goes even further then. Not only is blue hydrogen only marginally better than grey hydrogen, for heating homes it is actually worse than just burning the natural gas in the first place! It is easy to see why there has been a backlash: how can blue hydrogen, much touted by the industry as a ‘greener’ alternative, be worse overall than fossil fuels? It is important to tease out the points of contention here, starting with those made in the H&J paper and then stacking them up against what can be seen in industry today.
Use of blue hydrogen
H&J focus very heavily on the use of hydrogen for heating buildings and compare it very unfavourably with natural gas. This is misleading, however. Despite calls by some, such as the Hydrogen Council, a multi-stakeholder CEO-led global initiative, heating of homes with hydrogen will be a fraction of hydrogen usage at best, likely coming only after 2030 and only in certain situations in which other clean and more efficient technologies cannot be adopted. The majority of hydrogen usage will be used in industry and refining (as it is today) with big developments also in transportation, for example in the use of ammonia and methanol liquid fuels.
Low Carbon capture rates of blue hydrogen
H&J focus on a form of hydrogen production called steam methane reforming (SMR) wherein heat and pressure are used to bombard methane and release the hydrogen.
“The vast majority of hydrogen (96%) is generated from fossil fuels, particularly from SMR of natural gas but also from coal gasification.”
The CC rates of SMR are quite low, modelled at 76% in the H&J paper. This is due to the flue gas being diluted by the natural gas used, making it more difficult to pull out the CO2.
The focus on SMR is important, as although it is currently the dominant form of hydrogen production, other methods are on the horizon, namely Autothermal reforming (ATR). ATR is an alternative technology in which the process itself produces the required heat. This means that all related CO2 is produced inside the reactor, resulting in a more concentrated flue gas stream that, when compared with the SMR process, allows for 95% or higher CC rates..
Yet ATR is not mentioned at all by H&J and even within SMR, they seem to have their numbers wrong. The number of projects using CC with SMR according to H&J are:
“As of 2021, there were only two blue-hydrogen facilities globally that used natural gas to produce hydrogen at commercial scale.”
For this, they cite the Global CSS Institute’s ‘Global Status of CCS’ report, which states that:
“Today there are four industrial-scale SMR hydrogen facilities with CCS worldwide, producing a total of around 800,000 tonnes of low-carbon hydrogen per year.”
Whether H&J have a definition of commercial scale is unclear, since they do not state so in their paper, but it is telling that they did not see this statement in their own reference. This also focusses on SMR only. By the end of 2021, there were 16 projects generating hydrogen from fossil fuels with CCUS, 10 of which are commercial-scale plants. Four of these are at oil refineries and three are at fertiliser plants. Notably, six are retrofits of existing sites.
The focus on SMR might be reasonable when judging blue hydrogen production now, but when looking to the future, we should also consider the technologies that are on the horizon. JHaT specifically mentions concerns over upcoming blue hydrogen projects in the UK. In fact, two major projects in the UK, HyNet and H2H Saltend will use ATR technology. A good sign for the technology being used. Unfortunately, for both projects, the carbon will be stored and not used for greater benefit. This is a separate issue but does speak to the fact that blue hydrogen projects run the risk of taking the best economic case in storing the carbon, instead of the best environmental case of using it to further abate GHG emissions. This aspect of contributing to the circular economy is baked into the EU’s Taxonomy for environmentally sustainable economic activities and should not be forgotten when discussing blue hydrogen projects.
High fugitive emissions of blue hydrogen
A major criticism of blue hydrogen is the fugitive GHG emissions throughout the process. H&J describe their rationale for measuring fugitive emissions and focus on the level of methane emissions that are often overlooked in these processes. Methane is a vastly more potent GHG than CO2 and remains in the atmosphere for a much longer time.
Since SMR involves the use of methane as a raw material, the suggestion that significant levels of this gas escape is fair. These are called upstream fugitive emissions and refer to the methane that escapes into the atmosphere before it can be processed, thus contributing to climate change. The values for upstream fugitive emissions of methane according to H&J are assumed to be 3.5%.
This figure of 3.5% took many in industry by surprise. In 2019, the actual recorded value of fugitive methane emissions was 0.23% (Oil and Gas Climate Initiative (OGCI) figures), with values recorded by Equinor in their sustainability report to be even lower at 0.03%.
So why do H&J calculate fugitive emissions at a level that is magnitudes higher than the industry records? They are clearly using a different methodology, perhaps one that is more trustworthy than the self-reporting of private industry.
Firstly, we need to look at the assumptions in the H&J paper. They state that:
“Here, for our default estimation of the greenhouse gas footprint of gray hydrogen, we rely on a recent synthesis on “top–down” emission studies.”
The reference they use for these estimates? A chapter in ‘Environmental Impacts from Development of Unconventional Oil and Gas Reserves’ written by Howarth himself, which was in press at the time the Blue Hydrogen paper was written, so was not possible to verify right away (although to be favourable, let us assume that the peer reviewers had access to it). They do however allude to the fact that the reference comes from satellite and airplane flyovers from 20 different studies in 10 major natural gas fields in the United States and then take the average of those values. This is, in their own words, “a good estimate for the upstream emissions that occur in the gas fields.” Not bad, even if Howarth does say so himself.
This reference, gives a value of 2.6% for upstream fugitive emissions. H&J then add 0.8% for emissions that occur in transport after processing (the reference for this is again a paper by Howarth in the Journal of Integrative Environmental Sciences). Combined with the initial 2.6% figure, this gives a total of 3.4% in fugitive emissions. The remaining 0.1% comes from methane being burned by the natural gas industry to power natural gas processing and transport. So, 3.5% in total, but taken from self-referenced academic papers. This is not bad in and of itself, but it does add a layer of obfuscation and takes a little digging to pull out where the numbers actually come from. To do this, we are going to have to dive into the figures from some of these references.
The book chapter that provides the average of 20 estimations of fugitive emissions ranging from 0.2% to 17% above is now available. Interestingly, the very highest and lowest estimations in this range come from the same author, Pieschl et al. This provides a nice comparison since we have the same author providing vastly different figures.
The highest comes from the Los Angeles basin in California, a region of extremely low natural gas production at the time. Peischl’s remarks on the more recent, lower value of 0.2% are:
“The regions investigated in this work represented over half of the U.S. shale gas production in 2013, and we find generally lower loss rates than those reported in earlier studies of regions that made smaller contributions to total production. Hence, the national average CH4 loss rate from shale gas production may be lower than values extrapolated from the earlier studies.”
It would seem therefore, that the lower value would be the more accurate one. It is after all, more recent and based on a much wider range of sites. Would that it were so simple. Pieschl goes on to list some more values:
The range is clearly huge, but when H&J then go on to provide a sensitivity analysis to include two lower levels of methane emissions. In fact, they omit these figures completely from their analysis. They use instead values of 2.54% and 1.45% for the lower end of the scale instead of any of the much lower values from their own sources. This is part of their basis for the unfavourable comparison with natural gas for heating homes (which as we have seen, is unlikely to be a major use of hydrogen anyway).
The other thing you might notice is that all of the estimates by H&J are from quite dated sources, most of which are before 2016, so at least 5 years old by the time their Blue Hydrogen paper was published. Perhaps because for an academic paper, they felt they had to use academic sources, and as such they eschewed the lower industry figures. From the outside, it is difficult to know which figures to trust. Thankfully, more recent data are available and perhaps with these, we can get a better handle on where the true value lies within this range. These come from 2021 estimates made by the IEA in collaboration with Kayrros, an earth observation firm.
From this, global methane emissions were estimated at around 570 Mt. Fugitive methane emissions from natural gas activities specifically are responsible for about 40 Mt of methane (or about 1.5% of global GHG emissions). This gives a rough estimate of fugitive emissions of 7.4% — higher than both the industry figures and even H&J’s average figure. So is the actual value even worse than we thought?
Yes and no is the answer to that. Taking a global look at fugitive emissions (in this case figures for both gas and oil are included) we see an average of 10%. When looking more closely however, we see that there is huge variation from region to region. There are lower values for the EU (1%) and the U.S. (8%), while the global average is skewed by higher values coming from Venezuela, Iraq, and Turkmenistan, each with values exceeding 50%.
So, while the methodology of H&J to find their value of 3.5% fugitive emissions is riddled with problems, they do land on a number representative of the most recent and accurate readings, perhaps even significantly lower. What is clear from all of these numbers, is that fugitive emissions from natural gas vary wildly and are a direct consequence of the technologies used and the regulations in place to control them. Just because there are high fugitive emission levels in some regions, does not mean that that needs to be the case in the future. In short, it is something we can control.
Reducing fugitive methane emissions
So what can be done in this regard? According to the IEA, at least 50% of global (fugitive) methane emission from natural gas activities could be saved by using technologies and approaches that would pay for themselves through the captured methane that can be sold. This would be by a mixture of applying strict regulatory measures on reporting, and providing the right information to industry actors about the win-win technological options available.
IEA analysis estimates that it is technically possible to avoid around three-quarters of today’s methane emissions from global oil and gas operations. Established policies (including leak detection and repair (LDAR) requirements for fugitive sources, equipment mandates for sources known to emit significant volumes of methane, and measures designed to limit non-emergency flaring and venting) have proven both effective and relatively straightforward to implement. Most standards in this category do not require a robust measurement-based monitoring regime to verify compliance, although a quantification and reporting system is usually necessary.
Established policies can have a huge impact on reducing fugitive methane emissions. Source: IEA, Methane abatement potential of well-established policy measures, IEA, Paris https://www.iea.org/data-and-statistics/charts/methane-abatement-potential-of-well-established-policy-measures
Significant fugitive emissions could therefore be abated rather easily and at little cost. This has to be a consideration for regulators and policy makers on future blue hydrogen projects.
Conclusions
The high-level conclusions of the H&J’s Blue hydrogen report are correct: green hydrogen produced from renewable energy is much better for the environment, and there are hidden emissions within blue hydrogen that must be accounted for. Whether these emissions make it worse or only marginally better that grey hydrogen is unclear at this point.
There are major problems with H&J’s paper and with JHaT’s claim that it is biggest scam in history. Both major errors are in the use of outdated sources. On the one hand, they focus on SMR technology, which is clearly not going to be the major form of blue hydrogen moving forward and as a result underestimate CC rates. On the other, their use of outdated values for fugitive emissions, even if they omitted the lowest values, may have actually underestimated the problem.
The need to reduce fugitive emissions has been widely acknowledged by industry. The OGCI aims to improve methane data collection and develop and deploy cost-effective methane management technologies; with a target to reduce the collective average methane intensity to ultimately achieve a level of 0.2%. As we have seen however, there is a huge range of values worldwide for methane fugitive emissions, partly due to reporting differences, and partly due to varying engineering and infrastructural aspects. The results seen from established policies by the IEA clearly go a long way to reaching this level, but it is up to regulators to make sure that they are enforced.
As ever, details matter. To dismiss blue hydrogen altogether would be a mistake, but so would blanket approval, which runs the risk of enabling greenwashing. We should not let perfect be the enemy of the good: the availability of RES will not be enough to fuel the required hydrogen production under a net zero scenario, so we should look to other solutions to bridge that gap. This is especially true when there are heavy industries in urgent need of decarbonisation — we simply cannot wait until 2050 to start these processes.
Shining a light on the issue of fugitive emissions will push regulators and stakeholders to demand more of industry in these regards. So too will highlighting recent advancements in blue hydrogen technology, like ATR, which can drastically increase the CC rate and lower emissions further. It is quite clear already that the future of blue hydrogen will not be SMR, but this needs to be continually reinforced to avoid setting up less efficient facilities.
H&J highlight other issues that should be considered — namely what should be used to power the CC at the blue hydrogen plant? If it is the abundant sources of natural gas available to the plant rather than renewable energy, then it unnecessarily increases GHG emissions. What should the hydrogen be used for? If it is for heating homes as the Hydrogen Council suggests, it could even lead to an increase in natural gas usage compared to today (hence the cynicism around the fossil fuel industry-led council). However, their heavy focus on the weaknesses of hydrogen for heating homes is something of a red herring as it is likely that most of the hydrogen production will be used in heavy industry and transport, with only a fraction being used in buildings. Lastly, what should the CC be used for? For enhanced oil recovery as suggested by the JHaT vlog (which would violate the EU Taxonomy’s requirement to “do no significant harm”) or to abate emissions in the concrete and chemicals industries, or even combine with the produced hydrogen to generate synthetic fuels (such as e-methanol).
Blue hydrogen is not a scam; it is a necessary step to net zero, but one that must be done correctly. This will require transparency on all fronts, from industry, regulators, policymakers, and from its detractors, so that we can transition to a cleaner economy.
